Hi!
I´am running a xdmcp server on my computer at home.
From my clients at home everything works fine, but when I try to connect from my client at work, witch is behind i firewall, things goes wrong.
If I start iptraf on my server, and then try to connect from work, I can see my connections, but they are from my local ip at work.
I get something like 192.168.46.110 at port 6000 (my client at work) connections. So i understand that my xdmcp gets a bit confused and dont to where to send the response.

I know that I could use X forwarding with ssh and so on, but right now I would like to use xdmcp.
I could also setup a vpn connection, but I don´t have the permissions to install that kind of software on my computer at work.

Any ideas anyone?

XDMCP uses UDP port 177, so if you can't run that past the firewall then it may not work.

Rather than than doing this way I'd strongly recommend setting up VNC, and port forwarding it through SSH. X is notoriously demanding on bandwidth, which makes it unsuitable for remote access. As you may know, it also lacks encryption. Without a VPN, SSH is basically the only really secure remote access channel.